Sgribnee



(No Modelf) Y SELF SWITCHING SIGNAL BELL.Y

No. 252,266. Patented Jan. 10,1882.

I a l UNITED STATES PATENT OFFICE.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE WESTERN ELECTRIC MANUFACTURING COMPANY, OF SAME PLACE.

SPECIFICATION forming part of Letters Patent No. 252,266, dated January 10, 1882.

Application filed April l2, 1881. (No model.)

To all lwhom. it may concern:

Beit knownthat I, CHARLES E. SCRIBNER, of Chicago, Illinois, have discovered certain new and useful Improvements in Self-Switching Signal-Bells, of whichthc following is the specification.

In a telephone-exchange system where the outer ends of the individual telephonelines are grouped together by a common line, and the return-circuit ot' the signal-battery composed of the lines of the group which happen to be connected with the common line at the time the signal is sent through a given subscribers bell from the central office, it has been. proposed to polarize the bells to respond only to currents of a given polarity of battery, so that when this polarity is directed to the bell of any individual line the opposite polarity will be directed to the bells of the lines of the re` turn-circuit, so that the former only will ring. There will be ordinarily so many lines in the return-circuit that the portion of the returncurrent passing through the bell of one of the lines will not be strong enough to cause it to ring. i

My invention relates to the signal-bells used in this system of telephone-exchange, but may be usefully employed for all analogous purposes.

My invention consists in a switching device so combined with the bells that the signallcurrent is grounded just before the hammer reaches the bell in the line of the outgoin g current. The circuit is then for a moment divcrted from the common line directly to ground. I thus prevent ringing the bells in thelines of the return-circuit.

In the drawing Figure l, A, B, and C are subscribers stations, which may b'e provided with any of the well-known outfits. I have shown detail sections of the signal-bells and the individual circuits connected at their outer ends. The individual lines extend to the cenA tral office, and there pass through their respective switches to the com-mon line of the listening operators telephone to ground in the usual manner. Suppose subscriber at station A has been called for, the switchman, by connecting battery a with bolt b, sends a current to the line of the subscriber wanted. The cur- 5o rent may be traced in the tirst place, as indi cated by line c, through the coil of the electro` magnet and by lille d to the yarmature e, and thence by linefto the common line or pointg, and thence by the circuit of lines hand h back 55 to the bolts i and t" and to groundas shown.' This is the first circuit; but the instant the armature moves sufficiently to bring point k into contact with the point Z'the circuit is changed and the current diverted from line e 6o to ground-line fm, at station A. It is evident that the bell at station A, when in the position shown, would shunt the circuit otbattery a from the line f h and from the bell at station C. The current thus shunted would go to 65 ground by ground-contact l. Thus, it the bell at station B were cut out entirely, the two remainin g bells would be operative. In this way I am enabled to ground the circuit of a given line at the common line before the bells in the 7o lines of the return-circuit can ring. The initial current may be sufficient to move the armatures of the bells or annuncia-tors of the return-circuit very slightly, but no trouble can arise from this cause.

I claim- Y 1. The circuit ot' a battery through three or more electric bells, in combination with said bells and a ground-contact near the armature of the tirstbell, the succeeding two or more 8o bells being placed one in each of the branches of the derived circuit, which extends from the armature of the first bell through the said two or more bells to a common line, whereby the current `is 'directed automatically to ground, 85 and thus momentarily cutoff from the branches of the derived circuit, substantially as and for the purpose speciled.

2. `The combination of a battery, with three or more electric bells placed in the circuit of '9o said battery, said circuit being connected with the armature of the first bell by line d, and eX- tending thence in derived circuit through the `two 4or more succeeding bells, one bell beingin each branch of the derived circuit, thebranches 95 uniting in a common ground-line kin which is placed the operators telephone, and contactpoints 7c l, whereby the current from the batf bell, substantially as and for the purpose specitied.

3. The circuit of batteryc through switches .b and 'if to ofround in combination with two electric bells in circuitlbetween said switches, a branch circuit trom the armature of the first bell to ground, and means. asdescribed,\vl1ere by the current is directed automatically to ground through' said brauch at each stroke ot' the first bell, thus preventing the second bell from ringing, as and for thepurpose set-forth.

v4. The combination of three or more electric bells, with their armatures severally placed in. distinct branch lines, an outer common line, a

common ground-line at the-central office, the

coils of the electro-magnets ot the bells respectively in the circuit ot' the branch lines which connect with said armatures, switching apparatus in each line or branch, and a groundd contact, and an automatic shunting device near the armature of each bell, whereby any given line may be separated from said common ground-line and closed to battery, and thecurrent shuntcd to ground through the groundcoutact of the armature of the bell in the line thus closed to, battery, substantially as and for the purpose specified.

5. The combination ot' three or more electric bells, each placed in 'a different branch of a group ot' telephone-lines, with switching apparatus in each branch, between the ground and bells, and automatic switching devices, one device for each bell, whereby any line may be lconnected to battery, and the current thus directed through said given line may be shunted from the bells of the otherlines of said group, substantially as and for the purpose specified.

HARLES E. SCRIBNER.

Witnesses:

WILLIAM L. GRANGER MrLo G. KELLOGG. 

